A prior art search uncovered the following references:
Microwave Filters and Circuits (Academic Press, 1970), FIG. X.4.(b), p. 300, shows what is meant by a current balanced output. This reference teaches away from the instant transformerless current balanced amplifier in that it states; "An ideal [voltage or current] balun can only be approximated at low frequencies by a combination of ideal transformers."
U.S. Pat. No. 4,006,428 shows a detector circuit 156 comprising current sources 232 and 234 supplying transistors 216 and 218, respectively. However, the circuit is not a current balanced amplifier as in the present invention, because the presence of diodes 236 and 238, which drain off excessive current from the current sources, forces the output voltages of the circuit to be functions of fixed reference points. If this excess current were not removed, transistors 216 and 218 would saturate, and 232 and 234 would cease being current sources.
U.S. Pat. No. 4,061,932, while showing current sources supplying transistors, is a comparator operating in a saturated mode, and therefore is not a linear amplifier as in the present invention.
U.S. Pat. No. 3,644,838, while showing current sources supplying transistors, is not a current balanced amplifier as is the present invention.
U.S. Pat. Nos. 4,019,118 and 4,079,332 illustrate differential amplifiers, not current balanced amplifiers as in the present invention.